Interlocking honeycomb-cored panel system for construction of load supporting surfaces

ABSTRACT

A reusable panel system for the construction of load bearing surfaces, such as temporary or semi-permanent roadways and equipment support and work surfaces laid out over geologically unstable surfaces or over wet-land marshes. The individual panels of the present invention may interlock on one or more sides to form stable and continuous load bearing surfaces.

BACKGROUND OF INVENTION

The present invention relates to a reusable panel system for theconstruction of load bearing surfaces, such as temporary orsemi-permanent roadways and equipment support and work surfaces laid outover geologically unstable surfaces or over wet-land marshes.

When performing operations with heavy equipment in a remote location, itis often necessary to provide a firm, stable and continuous surface tosupport such equipment. For example, when drilling an oil or gas well ina remote location, it is often necessary to provide work surfaces usedduring the drilling process. It is also advantageous to provide one ormore roadways to allow access to and from the well-site. Such a surfaceshould be able to support the very heavy equipment used in suchoperations and able to withstand sever weather. Often the ground is wetand they may include marsh, bog, and/or slippery clay earths. The panelsshould be easy to install and able to provide sufficient support toallow operations under severe and difficult ground conditions. Thepanels may also be easily removable, with minimal impact to thesurrounding environment.

Historically various solutions have been used to meet theserequirements. Each has its advantages and disadvantages.

In the past, roadways were made of planks, boards or logs laid out invarious configurations and often nailed together. These roadwaysrequired an immense amount of labor to complete and were essentiallyimpossible to remove. There are many areas throughout the wilds ofCanada and the United States where evidence of these roads can be found50 or more years after they were initially used.

An improvement on these systems is the construction of wooden mats,often made of Oak, constructed and nailed together at a factory locationand then transported to the field. The mats are then interconnected andnailed together to provide a more or less continuous surface. However,the gaps in the materials allow the wet ground under the mat to “pump”material up through the gaps as heavy equipment moves over the surface.This creates a void in the ground under the mat and causes the mats tobreak and splinter. Further this “pumping” action often causes the matto be buried, necessitating the addition of further layers of mats.These shortcomings result in mats that are difficult to remove when thework is finished. Another disadvantage is the weight of the matsthemselves, when new and dry they are often over 2,000 lbs each, whenused and wet the weight can more than double. This requires the use ofvery heavy equipment to move and position the mats.

A further difficulty with these wood mats is they suffer fromsignificant rotting problems. This rotting, coupled with the foresaiddifficulty of breaking and splintering of individual boards causessignificant expense in repairs and maintenance to the mats.

Often wooden and other mats systems are not substantially connectedtogether. As vehicular traffic moves across the surface the mats mayseparate or “walk” apart. The resulting discontinuous surface createshazards for transportation and workers, further it exacerbates the“pumping” action of the mats.

Recently some polymeric load bearing mat systems have been proposed. Forexample, U.S. Pat. No. 4,629,358 to Springston discloses a mat systemfor the construction and repair of airfield surfaces. It is made offiberglass reinforced plastic and is filled with hollow inorganic silicaspheres.

U.S. Pat. No. 6,695,527 to Seaux et. al. discloses a mat system usefulto create a load bearing ground surface. The mats of the system areformed to be laid out over a surface with overlapping edges. The matsare each formed of two halves, an upper half and a lower half. Thehalves include a surface, which will face outwardly on the final mat,and a honeycomb surface, which will be positioned inside the mat whenthe two halves are secured together to form the mat.

SUMMARY OF INVENTION

A panel system has been invented for use in the construction of loadbearing ground surfaces.

In accordance with a broad aspect of the present invention, there isprovided a load bearing structure comprising a panel having at leastthree sides. The panel can be formed of a honeycomb core located betweenthe upper and lower surfaces of the panel. A continuous layer cansurround the honeycomb core. One or more connector means may be locatedon at least one side of the panel.

Selected edges of the panel may, in one embodiment, have a wedge-shapedconfiguration. In another embodiment, the panel may include a lappingledge along one or more selected edges.

If desired, a panel can be textured, treated and/or coated with avariety of slip-resistant and/or chemical and/or fire resistant coatingsto meet the needs of various applications. Furthermore, the panels maybe colored to provide high-contrast surfaces in order to enhancevisualization of the ground support.

In a further embodiment, the panel can be modified to includestress-strain sensors that can function to give real-time telemetricdata useful in determining the response of the panel under particularfield load scenarios.

A light-weight panel is thereby produced with consequently exceptionalhandling capabilities.

BRIEF DESCRIPTION OF DRAWINGS

Various embodiments of the invention are illustrated in the followingdrawings:

FIG. 1 is a top plan view of a load supporting panel having awedged-shaped edge configuration.

FIG. 2 is a side elevation view of the panel of FIG. 1.

FIG. 3 is an end elevation view of the panel of FIG. 1.

FIG. 4 is a section view of the panel of FIG. 1 connected to a secondpanel.

FIG. 5 is a top plan view of a plurality of load supporting panelsconnected together.

FIG. 6 is a side view of two load supporting panels connected together.

FIG. 7 is a top plan view of an alternative embodiment of a loadsupporting panel having a wedge shaped edge configuration.

FIG. 8 is a top plan view of an alternative embodiment of a loadsupporting panel having a wedge shaped edge configuration.

FIG. 9 is a top plan view of a plurality of alternatively configuredload supporting panels connected together.

FIG. 10 is a top plan view of a load supporting panel having a lappingledge configuration.

FIG. 11 is a side elevation view of the panel of FIG. 10.

FIG. 12 is an end elevation view of the panel of FIG. 10.

FIG. 13 is a sectional view along line XIII XIII of FIGS. 1 and 10.

DETAILED DESCRIPTION

The panels of the present invention may offer a durable, reusable systemfor construction of roadways and other ground support surfaces. Thepanels can be assembled to create work surfaces of various dimensions.Because the panels are designed to interlock with one another they canbe connected together in a wide number of combinations to provide thecorrect alignment for any ground support application. This flexibilityof assembly, along with the durability of the panels allows for quickand easy installation, usually requiring only one layer of panels onvirtually any ground substrate. The panels may be formed to bepositively buoyant to float on water, to enhance their usefulness.

Referring to FIGS. 1 to 3, a panel useful in the system is provided withan expansive upper surface 10 and a lower surface 12. A panel mayinclude a wedge-shaped edge 14 along one or more selected edges. In theembodiment shown, all the sides of the panels have a wedged-shaped edge.A wedge-shaped edge may be either descending (from the top to the bottomof the panel) or ascending (from the bottom to the top of the panel) inorder to permit an edge of one panel to be overlapped or underlappedwith an adjacent panel. For example, the side edge surface of the panelmay intersect with the upper and lower surfaces at other than 90° suchthat the thickness tapers. It may be useful to form the panels withcorresponding wedge-shaped edges, such that they can be fit together.

A panel may be connected to one or more other panels through connectormeans. In one embodiment, the connector means may be located around theperimeter of the panel, such that each panel can be connected to otherpanels in a wide array of different configurations. For example, theconnector means may be located between 2 and 14 inches from the outsideedge of the panel. In the panel illustrated, the connector means arealignment apertures 16 that extend through the panel between the uppersurface 10 and the lower surface 12 of the panel. Such apertures areformed to align with apertures on other panels to be joined together andto accept and retain a fastener or other component, such as a screw,bolt, rivet, pin, lock, nail, stake, wire, etc. FIG. 4 shows adescending wedged shaped edge 14 of one panel and an ascending wedgedshaped panel of a second panel 18 joined by connecting means thatincludes apertures 16 through the panel and an assembly that includes abolt 20 and a nut 22 each having flanged edges that engage the panelabout the aperture. In the illustrated embodiment, apertures 16 arepositioned on the wedge shaped edge 14. By joining the panels, multiplepanels become effectively a coacting surface suitable (as previouslydescribed) for use as road or work platforms on a variety of terrains.Other connector means may be used including but not limited to:apertures formed to accept and retain lock pins, such as those shown inU.S. patent application 2002/0187017 or other pins; pins formed ormounted on one panel edge and holes to accept the pins on other panel'sedges to be joined together; hook and loop fasteners, such as Velcro™;removable rivets; clips; buckles; clasps; clamps; braces; grips; locks;nails; stakes; wires; etc. The connector means may be formed on thepanel, connected to the panel during manufacture or separable therefrom,as desired, with possible consideration as to the form of connectormeans used.

Referring to FIGS. 5 and 6, a plurality of panels can be laid over aground surface in a single layer with their edges 14 overlapping. Theindividual panels of said system are restrained from horizontal movementby frictional contact with the underlying terrain, by mechanical contactand connection with adjoining panels, as by engagement by connectormeans 20 and, where necessary, by affixing the individual panels to theground by other mechanical means such as with stakes.

The panels of the present invention may be impermeable, so that fluidscannot seep into or through the body of the panels. This reduces and mayeliminate the “pumping” action associated with some other work mats asdescribed previously. By reducing pumping action the panels may also beeasier to pick up for reuse and may cause only minimal grounddisturbance after they have been removed.

Each panel may be formed with a continuous outer surface, such thatthere are no gaps or channels for the accumulation of mud, ice and otherdebris.

The dimensions of the panels of the present invention can easily bevaried with changes to production tooling. In one embodiment, the panelsmay be 7.5 feet by 14 feet so that they can fit into an ISO standardcontainer. The work surface of each such panel when assembled withadjacent panels overlaid and attached can be 6.5 feet by 13 feet.

Other sizes and shapes of panels can be easily manufactured in order tocustomize the panels for particular applications. Panels of differentdimensions can, for example, be constructed to allow for curves, slopesand other deviations in roadways and other surfaces. FIGS. 7 and 8 showfor example, a panel having a trapezoidal configuration having a shortend edge 26 and a long end edge 28 and side edges 30. It should bestressed again that other configurations could be manufactured. All edgelengths may be varied as shown between FIGS. 7 and 8. As well, panelshaving various different thickness may be used. FIG. 9 shows a pluralityof panels of different dimensions interconnected to one another so thatthey can be laid to form a curved roadway or other deviated surface.

FIGS. 10 to 12 refer to an alternative embodiment of the panel. In thisembodiment, the panel useful in the system may be relatively thin withan expansive upper surface 36 and lower surface 32. The panel mayinclude a lapping ledge 34 along one or more selected edges. Lappingledges 34 may be less than the full thickness of the panel to permit anedge of one panel to be overlapped or underlapped with an adjacentpanel. It may be useful to form the panels with corresponding lappingedges, such that they can be fit together. For example, each panel mayinclude a ledge extending from its upper surface 38 on one or more sidesand a ledge extending from its lower surface 34 on one or more othersides. In one embodiment, each panel may be formed as a square orrectangle and may include a ledge extending from its upper surface ontwo adjoining sides and a ledge extending from its lower surface on theother two sides. These ledges may be substantially one half the paneledge thickness so that the ledges can be overlapped. The ledges mayextend out from the panel edge a distance, for example about one foot,that creates some resistance to mud and liquids passing through theinterface of the lapped ledges.

Connector means may be molded into the panel or connected to the panelduring manufacture. In the embodiment shown, substantially rigidprojections 37 such as a pin, bolt, screw, etc, are connected to or formpart of the ledge extending from the lower surface of the panel 34.Apertures 16 located on the ledge extending from the upper surface ofthe panel 38 are formed to accept and retain the substantially rigidprojections 37 of an adjacent panel.

The edges of the panel may also be reinforced to constrain anycompression at the edge of the panel and to protect the edge of thepanel from damage. This edge reinforcement may be provided in variousways and from various materials including but not limited to: fiberreinforced materials, such as for example, pultruded fiberglass,polymeric rods, for example various plastics (such as polyolefin), wood,steel, aluminum and other commonly available commercial materials suitedto the requirement. The reinforcement material may be placed at variouspoints of the edge of the panel, incorporated into the wedge itself,placed parallel to the wedge on the vertical plane, etc.

The present panel may include a honeycomb core and a fiber reinforcedlayer thereon. In one embodiment, a honeycomb core manufactured ofpolypropylene thermoplastic is sandwiched between layers of fiberreinforcements. In other embodiments, the honeycomb core material may beselected from a variety of commercially available core materialsincluding metal such as aluminum honeycomb, resin reinforced paperhoneycomb and other commercially available honeycomb core materials. Thereinforced layer may completely surround the honeycomb-core so that itis not open on the edges of the panel, thus forming a continuous layer.

Fiber reinforcements are available in a large number of fiberarrangements each with different characteristics that can be used toproduce desirable properties in variants of the present invention. Forexample, stitch-fiber matting may be utilized in order to increase thecompression strength of the panel. Reinforcing fibers may includefiberglass, carbon fiber, aramid fiber, or other commonly availablereinforcing fibers can be used alone or in combination. Thesereinforcing fibers can be impregnated with an adhesive and placed ontothe honeycomb core, or placed on the honeycomb core and infused with anadhesive. The panel may also be manufactured with the use ofthermoplastic adhesives.

A panel can be textured, treated and/or coated. Slip-resistant and/orchemical and/or fire resistant coatings/treatments may be used to meetthe needs of various applications. Additionally, the materials of thepanels, such as the coatings, may be colored to provide high-contrastsurfaces to enhance visualization of the ground support. A panel can berecoated at any time should the coating become ineffective due to wearor some other cause.

Referring to FIG. 13, a panel is shown in section. The panel includes: aslip resistant coating 46, such as sand particles (sand particles 20mils in diameter in about 5 mils of paint, for example); a surfacecoating 47, such as paint (10 mils of paint, for example); a fiberreinforced layer 42 (including two layers of fiber glass mat in epoxy,each layer about 1/16 inches thick, for example); a honeycomb layer 40(4 inches of honeycomb with 5/16 inches straws, for example); fuzz ontop of the honeycomb core with epoxy 44 (about 5 mils of epoxy, forexample); and barrier film 45 (5 mils of barrier film, for example) forreducing infiltration to the honeycomb layer 45. It is important tostress that these are examples and not limitations.

While the present invention provides a panel system for the constructionof load bearing surfaces, such as roads or work areas on unstable groundsurfaces, it can also be applied for use over conventional roadways androad and work surfaces to increase the load bearing capacity of thesurface. The panels are light weight. Consequently, with minimalequipment and manpower, the panels can be interlocked to provide saidwork surfaces that may exhibit durability and strength and then can bedisconnected, picked up and transported to another site for reuse. Thepanels can be manufactured using a variety of techniques, from moldedthermoplastics to fiber-reinforced composite structures made withthermoset resins.

The panels can be altered to make them useful in other applications suchas trench covers, airport taxiways, floors for portable buildings,walkways, portable docks, trench shoring, or other such uses as becomeapparent. These alterations can involve resizing the honey-comb core,the reinforcement layer, or the use of different outer coatings.

To produce a panel, a mold may be manufactured, for example, out oflight gauge steel. The mold may be tightly sealed to prevent air leakageduring the vacuum phase of the manufacture. The inside surface of themold can be textured either by directly embossing the steel, or byadding a layer of plastic that has the reverse image of the desiredsurface texture. This mold inside surface forms the top surface of thepanel. The inside of a vacuum bag used during the vacuum phase of themanufacture forms the bottom surface of the panel. This technique iswell known in the art as “vacuum-bag” layup.

The inside of the mold may be sprayed or waxed with a release compound,which is a material to which the adhesives used in the manufacture ofthe panel will not easily stick. This may be done to facilitate removingthe panel from the mold after it has cured. Reinforcing fiber materials,such as for example, fiber reinforcing cloth can then be positioned inthe mold. The cloth may be trimmed to fit the inside of the mold.

The fibers may be positioned before or after saturation with an adhesivematerial, which may be, for example, an epoxy resin. In one embodiment,a resin system may be used that is supplied by Dow Chemical available asDow Durakane 331 Epoxy™. Such a resin may, in one embodiment, be curedusing Dow Jeffamine D-320™ with the addition of an acceleratormanufactured by Huntsman Chemical called Accel 399™.

The polypropylene honeycomb core may then be set into the mold on top ofthe reinforcing fiber materials. In one embodiment, the honeycomb coremay be that supplied by Plascor and known as PP30-5-2™ PolypropyleneHoneycomb Core. PP30-5-2 has material density of roughly 5 pounds percubic foot of core. The core may be treated for adhesion to the fiberreinforcing material using various techniques known in the art. Thistreatment may be used to increase the adhesion of the reinforcing fiberto the core and can enhance the physical properties of the resultantpanel. The honeycomb core extends over most of the finished panel. Forexample, in one embodiment, the honeycomb core can extend toapproximately 90-95% of the overall size of the finished panel.

Prior to setting the honeycomb core into the mold a reinforcing edge maybe applied to the sides of the honeycomb. This reinforcement may includeany of various materials. In one embodiment of the present invention,the material used is a plastic such as polyolefin thermoplastic, (whichcan be in a triangular or rectangular form, for example), adhered withmastic, for example, made up of the epoxy resin formula and INHANCE™PEFfibers made of high-density polyethylene (HDPE) fibers. This product ismanufactured by the Inhance Group of Fluoro-Seal International, LP. Thefibers will be imbedded in the polyolefin.

With regards to the panel having the wedge shaped edge configuration,the wedge may be constructed by machining the honeycomb core to form thewedge configuration after the reinforcing edge is applied. Othertechniques to forming a wedge shaped edge may also be employed. Forexample, a separate wedge could be constructed from any rigid material,(such as plastic, etc.) and then adhered to the sides of the honeycomblayer prior to applying the layer of reinforcing fiber. This couldinvolve pultruding the entire wedge and then adhering a correspondinghoneycomb cut profile into the pultrusion. The wedge may then be adheredwith, for example, mastic to the honeycomb core.

A second layer of reinforcing fiber and adhesive, such as epoxy, maythen be laid on top of the honeycomb core. Corners and or edges may befinished by folding them in on themselves.

One or more materials, may be applied on top of the second layer, aswill be appreciated, to allow the panel to be vacuum bagged and whencured ease the release of the various materials from the panel itself. Avacuum may then be applied to the panel and the mold. The pressure ofthe vacuum causes the materials in the mold to consolidate and forcesany air entrained in the structure to be evacuated. The vacuum may bemaintained until the chemical exothermic reaction of the epoxy system issubstantially or fully complete such that the epoxy is substantially orfully cured.

The panel is then removed from the mold. The panel may then be trimmedto final specification.

Thereafter sufficient holes may be cut into the panel to provideapertures and/or so that connector hardware, such as aperturereinforcement pins, etc. can be glued into place using any of a widevariety of adhesive suitable for that purpose.

The panel may then be coated with an industrial epoxy coating suitablefor the chemical resistance and environmental resistance required forthe panel, depending on its intended application. For example, resinsand coatings may be selected to enhance chemical and/or fire resistance.As another example, coatings or resins may be selected to controlstatic, should this be required. These coatings may also be colored.Anti-static features may also be added to some suitable standardcoatings.

Alternately or in addition, a top-coat of anti-slip coating may appliedto the panel. One coating that may be used for this purpose is suppliedby Devoe Coatings and is known as DevGrip™. There are various grades ofthis coating available and the appropriate grade is selected dependingon the end use of the panel. The anti-slip coating may be colored aswell.

The panel may then be allowed to continue curing. Curing may beconducted slowly, for example over a number of days, or may beaccelerated, for example, by putting the finished panel into a heatedenvironment. In one embodiment, curing may be conducted at a temperatureof 160° F. or less for up to 48 hours.

A panel is thereby produced with a reasonable weight and consequently,reasonable handling capabilities. For example, in one embodiment a panelmeasuring 4.29 meters by 2.31 meters by 010795 meters may weigh lessthan 193 kilograms (14.075 ft by 7.575 ft by 4.25 inches weighing lessthan 425 lbs). The panel of the present invention may have a reducedweight over previous panels by the combination of the essentially hollowhoneycomb core providing spacing between thin lightweight reinforcedlayers that have extremely high strength to weight ratios.

As well, the panels of the present invention possess significantlybetter bulk properties over previous panels as a result of the materialsthat used are used in its reinforced layer. Bulk properties are theincreased physical properties such as tensile strength, compressivestrength and flexural rigidity. Further, by altering the density ormaterials of the honeycomb core, the cross-sectional thickness of thehoneycomb core or by altering the characteristics of the reinforcedlayer such as: changing the type of fiber reinforcement, its makeup orthe material it is made of; or by changing the adhesive resin many ofthe bulk properties of the panel may be altered. For example a panelwith more flexural rigidity could handle significantly more load on softground and could be made by the addition of more fiberglass and resin tothe reinforced layer of the panel.

In a further embodiment the panel be modified to include stress-strainsensors. The stress-strain sensors can function to give real-timetelemetric data useful in determining the response of the panel underparticular filed load scenarios. This information could be useful increating a modified panel to replace a panel or panels that are failingunder the specific circumstances present in the field at a uniquelocation. The stress-strain sensors may be attached to the panel byseveral different means, including but not limited to: encapsulating thesensors into the coating itself; or gluing the sensors onto the panel byusing any of a wide variety of adhesives suitable for that purpose.

It should be understood that even though numerous characteristics andadvantages of the present invention have been set forth in the foregoingdescription, the disclosure is illustrative only, and changes may bemade in detail, especially in matters of size, shape and arrangement ofparts within the principles of the invention to the full extentindicated by the broad general meaning of the terms in which the claimsare expressed.

1. A load bearing structure comprising: a panel having an upper and alower surface and at least three sides, at least one of the sidesincludes a wedgeshaped edge; a rigid honeycomb core between the upperand lower surface, a continuous layer surrounding the honeycomb core;and one or more connector means located on at least one side of thepanel.
 2. The load bearing structure as set forth in claim 1, whereinthe rigid honeycomb core is substantially hollow.
 3. The load bearingstructure as set forth in claim 2, wherein the rigid honeycomb core iscomprised of a substantially plastic composition.
 4. The load bearingstructure as set forth in claim 3, wherein the substantially plasticcomposition is polypropylene thermoplastic.
 5. The load bearingstructure as set forth in claim 2, wherein the rigid honeycomb core ismade from material selected from a group consisting of metal, resinreinforced paper, fiberglass, and wood.
 6. The load bearing structure asset forth in claim 1, wherein the substantially continuous layer iscomprised of reinforcing fibers.
 7. The load bearing structure as setforth in claim 5, wherein the reinforcing fibers are selected from agroup consisting of fiberglass, carbon fiber, aramid fiber, and anycombination thereof.
 8. The load bearing structure as set forth in claim1, wherein at least two adjacent sides of the panel each comprise awedge-shaped edge.
 9. The load bearing structure as set forth in claim7, wherein one wedge-shaped edge descends from the top to the bottom ofthe panel, and the adjacent wedgeshaped edge ascends from the bottom tothe top of the panel.
 10. The load bearing structure as set forth inclaim 8, wherein the connector means are located on each side of thepanel that comprises a wedge-shaped edge.
 11. The load bearing structureas set forth in claim 9, wherein the connector means are selected from agroup consisting of apertures, screw fastener, a removable rivet, aclip, a buckle, a clasp, a clamp, a brace, a grip, a bolt, a screw, alock, a nail, and hook and loop fasteners.
 12. The load bearingstructure as set forth in claim 1, wherein the connector means arelocated on the side of the panel with the wedge-shaped edge.
 13. Theload bearing structure as set forth in claim 12, wherein the connectormeans are selected from a group consisting of an aperture, a screwfastener, a removable rivet, a clip, a buckle, a clasp, a clamp, abrace, a grip, a bolt, a screw, a lock, a nail, and hook and loopfasteners.
 14. The load bearing structure as set forth in claim 1,wherein the substantially continuous layer is coated with a coatingselected from a group consisting of slip resistant coatings, chemicalresistant coatings, fire resistant coatings, color coatings, anti-staticcoatings, and any combination thereof.
 15. A load bearing structurecomprising: a panel having an upper surface and a lower surface, andside edges surrounding and extending between the upper surface and thelower surface, at least two adjacent sides of the panel form awedge-shaped edge; a substantially hollow honeycomb core between theupper and lower surface formed of a substantially plastic composition; acontinuous surrounding layer including reinforcing fibers selected froma group consisting of fiberglass, carbon fiber, aramid fiber, and anycombination thereof; and one or more connector means located on eachside of the panel on the wedge-shaped edges.
 16. The load bearingstructure as set forth in claim 14, wherein each side of the panelcomprises a wedgeshaped edge and wherein one wedge-shaped edge descendsfrom the top to the bottom of the panel and an adjacent wedge-shapededge ascends from the bottom to the top of the panel.
 17. The loadbearing structure as set forth in claim 16 wherein at least onestress-strain sensor is coupled to the panel.
 18. A load bearingstructure comprising: a panel having an upper surface and a lowersurface, wherein the upper and lower surfaces are offset relative to oneanother such that the upper surface forms a lower peripheral extensionand the lower surface forms an upper peripheral extension and whereinthe panel is surrounded by a substantially continuous layer; asubstantially hollow rigid honeycomb core between the upper and lowersurface; and one or more connector means located on at least one side ofthe panel.
 19. The load bearing structure as set forth in claim 18,wherein the substantially hollow rigid honeycomb core is comprised of asubstantially plastic composition.
 20. The load bearing structure as setforth in claim 18, wherein the substantially continuous layer iscomprised of reinforcing fibers selected from a group consisting offiberglass, carbon fiber, aramid fiber, and any combination thereof.